The present invention relates generally to industrial chemical conversion of wastes. In particular, it relates to conversion of organic and inorganic materials to useful fuels and other products.
Converting wastes to useful end products, such as fuels, has been the goal of considerable efforts. Several approaches to achieving this goal have been tried, including pyrolysis. While this invention is definitely not a variation on the art of pyrolysis, the original research which resulted in this invention was primarily in that field. Therefore, it is only fitting that any discussion of the background of this invention begin there.
The art of pyrolysis is reputed to have began in the 1500""s. It is presently described as the destructive distillation of any material. The original successful industrial results of this art were the production of coal tar and coal oil from the pyrolysis of coal. The second, coal oil, was widely used as an illuminating oil throughout the world until the development of kerosene during the early petroleum industrial development.
In the world""s oilfields, many thousands of barrels of crude oil have been burned as a result of early attempts at disposal. This xe2x80x9cwastexe2x80x9d crude oil was usually collected on waste pits on or near production facilities (called xe2x80x9cleasesxe2x80x9d) and refineries. There were numerous attempts to treat this waste in a way that would allow its useful recovery or conversion to a useful form. Pyrolysis of the waste was attempted but had many practical limitations. Close examination of attempts to address the problem of the proper treatment of this waste shows that the original inherent problems remain.
In the prior art the usual design and operating practice has been to place the feedstock in a retorting device from which the ambient atmosphere can be excluded, heating the materials to between 500 and 2,000 degrees F., and recovering the volatized and condensed materials in some form of collection vessel. The solids residues, generally characterized as xe2x80x9ccharxe2x80x9d are recovered in their combined form and usually disposed of as an industrial waste. However, there were and still are several problems resulting from such practices which make those systems impractical.
One of these is the problem of coking which resulted in all previous attempts from the deposition of heavy carbon deposits upon the interior walls of the pyrolysis retort system. This deposit increases in density and thickness to the point that it in effect acts as insulation, inhibiting the transfer of thermal energy into the system. There were additional problems with isolated buildups and concentrations of heat which often resulted in melt-downs of the retort walls resulting in catastrophic fires. This phenomenon has been observed in most of the other systems referenced. Many attempts have been made to prevent this problem, the latest being that described in U.S. Pat. No. 6,156,439 to Coffinberry issued Dec. 5, 2000 which suggests a coating on the interior walls of the retorting vessels and the balance of the system to resist the deposition of these materials.
An additional problem resulting from the coking phenomenon and the use of internal parts and components invariably results in the binding of these moving, especially rotating, parts and, with the complications resulting from the extreme interior temperatures, these moving parts can be destroyed. This was and is particularly true of interior coke-scraping and augering systems as disclosed in U.S. Pat. No. 4,439,209 to Wilwerding, et al., issued on May 27, 1984, where the scrapers (29) were repeatedly torn off and the evacuation auger (32) were prone to be ripped from their shafts and to stack at the end of their respective chambers as was demonstrated in 1987/88.
A related problem inherent in most prior art was that the introduced feedstock was dried into a cake on the interior walls of the retort and were then prone to rip the auger flites off their shafts and stack them at the end of the chamber. This was a particular problem of the design features of the system taught in U.S. Pat. No. 4,759,300 to Hansen, et al., issued on Jul. 26, 1988, when processing used petroleum drilling muds as well as in that disclosed in U.S. Pat. No. 4,412,889 to Oeck, issued Nov. 1, 1983.
Another problem invariably present in pyrolysis systems was and remains that of retroactive condensation reactions wherein, as the process progresses, hydrocarbon molecules are broken and the liberated hydrogen atoms are allowed to form hydrogen gas and to escape. As the remaining hydrocarbon elements are reformed they combine into progressively longer and more complex molecules until they become much like coal or coke. Many attempts have been made to address this problem over the years with the latest being U.S. Pat. No. 6,039,774 to McMullen, et al., issued Mar. 21, 2000.
Still another problem plaguing the practice of pyrolysis is that of the destabilization of the pyrolysis oils over relatively short time spans after production. The poor stability of pyro-oils has been mostly attributed to the high oxygenated compound content of these oils which gives rise to polymerization reactions and the subsequent increase in viscosity. This happens at any temperature and is accelerated by the presence of xe2x80x9cpyrolysis charxe2x80x9d in the stored processed oils. It often progresses to the point that the produced products are of even lesser value than the original feedstock materials. This process is well described in a paper: Pyrolysis Char Catalyzed Destabilization of Biocrude Oils presented by Foster A. Agblevor of Virginia Polytechnic Institute in 1997 to the ALCHE.
The prior art has produced systems that are extremely sensitive to variations in feedstock composition. To accommodate changes in feedstock, these systems must be modified.
In the past the attempted employment of lasers, ultrasound and microwave components in the systems has been confined entirely and exclusively to the production of thermal energy within the operating system. This is shown in U.S. Pat. No. 4,118,282 issued to Wallace on Oct. 3, 1978.
In all known instances there has been no attempt to maximize the transfer of thermal energy into the system or to recover spent thermal energy and re-introduce it to the processing system. (Re: all references cited, but particularly U.S. Pat. No. 4,439,209 issued to Wilwerding, et al., on Mar. 27, 1984.) This failure has occurred notwithstanding the fact that, in all known instances, the disclosed precesses are thermally driven. Not only has this resulted in wasting of fuels and energy, but it has also been a tremendous producer of thermal pollution. Often the furnace burner manufacturer states that the burner flame should be adjusted so that the exhaust stack temperature just above the retort is at approximately 450 degrees F. (re: Eclipse Boiler Division Instruction Manual # 179.)
Prior inventors have made many attempts to relieve the problem of sulfur/chlorine/fluorine contamination of both produced oils and gasses. These attempts have required the injection of contaminating slurries (U.S. Pat. No. 4,806,232 issued to Schmidt on Feb. 21, 1989 and U.S. Pat. No. 4,867,755 issued to Majid, et al., on Sep. 19, 1989) and other similar substances. Nowhere found are references to breaking the specific molecular bonds between these substances and their carbines carriers in order to remove and/or recover them.
In the past there have been no known attempts to recover the compressible gasses in their liquid forms. And while there have been attempts to operate such systems under an internal vacuum, this is not known to have been done in conjunction with the liquification of the compressible gasses.
Thus far there has been no discovery of the employment of catalytic elements that are energized by electromotive forces of any type in order to produce a desired or enhanced result.
In prior art the feedstock is introduced into the reaction chamber by means of a plunger mechanism (U.S. Pat. No. 4,439,209 issued to Wilwerding on Mar. 27, 1984) or by an auger screw mechanism using a single auger positioned within a channel or tube (U.S. Pat. No. 4,235,674 issued to Chambers issued on Nov. 25, 1980). These mechanisms are intended for use with solid and liquid feedstocks. However, they both are ineffective with liquids and do not prevent contact between the atmosphere and the solids or the liquids. (Usually the introduction of gases is not provided for.) Particularly with the utilization of augering systems, the augers tend to xe2x80x9cload upxe2x80x9d with solid feedstock and are unable to convey the materials into the system. This is particularly true with wetted feedstocks such as contaminated soils and other solids.
In all cases known, a particularly serious problem with rotating members of the system is the durability of the bearing and sealing systems for the rotating member joints. This was readily apparent from the description in U.S. Pat. No. 4,439,209 (Wilwerding) during demonstrations in 1987 and in U.S. Pat. No. 4,412,889 (Oeck).
In the prior attempts at waste conversion, the usual practice has been thermal or catalytic-assisted thermal cracking under high temperatures and/or pressures. These conditions often entail the use of temperatures in excess of 1,500 degrees F. and pressures in excess of 2,000 pounds per square inch during the process. These conditions necessitate heavy equipment that is not transportable with any measure of facility or ease.
Converting waste to useful fuels has also been the focus of federal research over the past decades. Many of these projects have been carried out under the auspices of the Idaho National Engineering and Environmental Laboratory (INEEL) under the jurisdiction of the Argonne National Laboratory operated for the U.S. Department of Energy by the University of Chicago.
One such project is described in the April, 1999 issue of the INEEL Quarterly under the heading of xe2x80x9cFrom the Cooking Pot to the Gas Tankxe2x80x9d. This is an attempt to more economically convert used cooking oils into synthetic Diesel using a newly developed catalyst. As another example, the National Renewable Energy Laboratory, under the direction of the U.S. Department of Energy, has on-going research projects in many areas including catalytic pyrolysis and synthetic gas (xe2x80x9csyngasxe2x80x9d) production.
However, there remains a need for an effective method and apparatus for converting a wide variety of materials, be they wastes or be they resources, to useful fuels and chemicals.
According to its major aspects and briefly recited, the present invention is a method and apparatus for the conversion of both organic and inorganic material into synthetic crude oils, gasoline and diesel components, synthetic fuel oils, carbonous materials, gases recoverable in compressed liquid forms, and gases incompressible into liquid forms. The present apparatus and method can operate on solid, liquid and gaseous materials in any combination and concentration and may include but are not limited to waste crude oils, dead animals, absorbency pads used in oil spill cleanups, waste tank bottoms, oil-based drilling muds, refinery and/or petrochemical wastes, spent solvents, contaminated soils and dirt, used cooking oils, used tire rubber and other rubber waste products, heavy oils, refinery residuals, contaminated fuels, waste plastics, municipal wastes and garbage, medical wastes, used lubricating oils, coal, oil tar sands, oil shales, agricultural products, bio-wastes or any other hydrocarbon-based material.
The apparatus includes a pair of retort vessels in communication with each other, one of which has two chambers. One chamber contains a fluidized bed of catalytic, feed and abrasive materials and the other a crusher mill. The vessels include lifting and stirring elements fixed to the interior walls to promote and help maintain a condition of fluidization of bed materials during operation. These vessels operate in the absence of atmospheric gases and at or below atmospheric pressure so as to help prevent the escape of pollutants into the atmosphere. Heat-collector/transfer members are attached to the exterior walls of the vessels to increase the heat collecting surface area of the exterior walls of the member in order to maximize the collection of thermal energy, increase the flow of thermal energy into said system, and reinforce and strengthen the exterior walls of the vessel. A thermal gradient is established in both or either one of the vertical and horizontal retort vessels and maintained during operation in order to create a xe2x80x9creflux actionxe2x80x9d. Finally, the apparatus employs a solids residue crushing and pulverizing section.
The present apparatus and method employs microwave, laser, maser, and/or ultrasonic energy either independently or in concert to promote and control the precise disassociation of the molecular or atomic components of the feedstock materials during processing.
The present apparatus and method produces useful solids, liquids and compressible, condensible gases for recovery and sale, and which in some cases are used by the process itself to reduce its own energy requirements or as carrier gases to move product through the retort vessels to more quickly and efficiently convey the volatized materials through and out of the system. Because of the extensive reformation that takes place, once processed, the waste feedstock cannot be identified from the final products. Compression of product gases results in a negative pressure within the system which helps prevent the escape of and promote the recovery of uncompressed products which are rich in hydrogen gas.
The design of the present apparatus has several advantages, namely, it has no internal moving parts within a part of a heated environment of the system; by its design and operation, it prevents the formation of xe2x80x9ccokexe2x80x9d and xe2x80x9ccakexe2x80x9d and fully controls the xe2x80x9cretrogressive condensation reactionxe2x80x9d within the system.
Energy considerations are carefully addressed in the present design. In order to be more thermally efficient, the design of the present apparatus also employs a combined condensation/thermal recovery process which, in thermal counter-flow, recovers spent thermal energy from the out-flowing produced materials while pre-heating the in-coming feedstock materials and thereby returns said recovered thermal energy back into the operating environment of said system. This combination condensation/thermal transfer unit is partially made of catalytic metals and other materials in order to begin the conversion process in the preheat stage. Even a portion of the product gases, recovered as condensed liquids, can be used as fuel for producing the heat for the present reactions. Furthermore, the thermal energy used in the process is not allowed to escape the system in the form of thermal pollution.
Another feature of the present apparatus is an auger system for the introduction to and evacuation of solids materials from the processing environment. This auger system consists of a double auger in-feed system which operates so as to positively displace the feedstock into the processing environment without blockage or other impediment, and an out-feed auger system consisting of a solids residue separation segment, a sliding valve segment to convey the solids residue into the auger channel, an auger within this channel which moves the residues away from the operating environment and a sliding valve component which allows the solids residues to exit the operating system without allowing the invasion of ambient atmosphere. The shafts of all augers can be hollow to permit conveyance of liquid feedstock, gaseous feedstock, or carrier gases into the operating environment or extract gases and volatized materials from the system.
Another important feature of the present invention is the use of abrasive materials in the vessels. Abrasive materials scrub the interior walls to prevent the accumulation of coke and cake, they abrade the feed stock particles as well as prevent clinkers from forming, and abrade the catalytic materials to clean them and thus avoid a condition known as catalytic poisoning.
One great advantage of the system and the process is the ability to reduce sulfur and chlorine contaminations in the produced products without regard for the contents of the original feedstock materials. These decontaminated produced materials may be, but are not limited to, crude oils, fuel oils, diesel fuels, fuels used in jet engines and turbine engines, and may be produced through the processing of contaminated fuels and other feedstocks, waste paint products and spent chlorinated solvents to name but a few.
Another use and benefit of this system and process is an ability to convert benzine-ring molecular forms into a straight-chain molecular form that is far less hazardous to both the population and environment.
Other features and their advantages will be apparent to those skilled in the art of waste chemistry from a careful reading of the Detailed Description of Preferred Embodiments, accompanied by the following drawings.